Golf Ball Compositions Comprising Elastic Proteins

ABSTRACT

The present invention is directed to golf balls having at least one layer formed from a composition comprising an elastic protein. Golf balls of the present invention include one-piece, two-piece, and multi-layer golf balls. In two-piece and multi-layer golf balls of the present invention, the elastic protein-containing composition may be present in a core layer, a cover layer, an intermediate layer (in the case of multi-layer balls), or a combination thereof.

FIELD OF THE INVENTION

The present invention relates to compositions comprising elastic proteins and the use thereof in golf balls.

BACKGROUND OF THE INVENTION Elastic Proteins

Elastic proteins are a class of materials which includes, for example, resilin, titin, elastin, abductin, collagen, and spider silks. Recent developments in genetic engineering have made possible the replication of partial genomes of various organisms to synthetically produce elastic proteins. For example, in a recent publication, “Synthesis and properties of crosslinked recombinant pro-resilin,” Nature, vol. 437, pages 999-1002 (2005), a method for producing crosslinked synthetic resilin is disclosed. The publication describes synthetic resilin as having superior resilience relative to high-resilience polybutadiene. The publication also describes synthetic resilin as being useful for industrial and biomedical applications, but its use in golf ball applications is not disclosed.

Golf Ball Design

Conventional golf balls can be divided into two general classes: solid and wound. Wound golf balls typically include a solid, hollow, or fluid-filled center, surrounded by a tensioned elastomeric material, and a cover. Resilience in wound golf balls is provided by the tensioned elastomeric material, e.g., isoprene rubber.

Wound golf balls have been replaced by solid golf balls, in both the marketplace and among the game's most accomplished players, as a result of the formulation of high-resilience synthetic rubbers, particularly polybutadiene, which provide for resilience in solid golf balls that is comparable to or exceeds that of wound golf balls. This development has led to design opportunities in multi-layer golf balls, wherein layers of different materials are used to provide various combinations of ball characteristics. For example, ionomer cover layers have been used to lower the spin and improve the durability of solid golf balls. Also, intermediate layers have been used to create balls that spin and, therefore, perform differently for different kinds of golf shots or for different types of players. Thus, the selection of various materials for use in cover, core, and intermediate layer(s) is of principal significance in modern golf ball design.

Despite the growth in design variation, polybutadiene remains the primary source of resilience in solid golf balls, because other materials that are used to form golf ball layers do not have the resilience of polybutadiene and/or lack the desired softness. For example, while some ionomers have good resilience, they can also have undesirable hardness.

In addition to the limited choice of suitable materials, golf ball design is also limited by diameter. Larger diameter adversely affects the aerodynamic performance of a golf ball. Therefore, with each added design element, e.g., an added layer or an added thickness to an existing layer, the volume of polybutadiene in the overall product may be reduced, which can lead to a reduction in resiliency. Several proposed solutions include the use of softer, high-resilience thermoplastic polymers and formulations of polybutadiene having higher resilience. However, these materials have not yet been formulated such that they can replace conventional polybutadiene as the primary source of resilience in golf balls.

Thus, there is a need in the golf ball industry for novel high-resilience, soft materials. Such materials may enable the incorporation into golf balls of soft centers, fluid-filled or hollow centers, and/or soft covers. The present invention describes such compositions and their use in a variety of golf ball core, cover, and intermediate layers.

SUMMARY OF THE INVENTION

In one embodiment, the present invention is directed to a golf ball having at least one layer formed from a composition comprising an elastic protein.

In another embodiment, the present invention is directed to a golf ball having at least one layer formed from a composition comprising an elastic protein, wherein the golf ball has a coefficient of restitution of at least 0.815 and an Atti compression of 90 or less.

DETAILED DESCRIPTION OF THE INVENTION

Golf balls of the present invention include one-piece, two-piece (i.e., a core and a cover), multi-layer (i.e., a core of one or more layers and a cover of one or more layers), and wound golf balls, having a variety of core structures, intermediate layers, covers, and coatings. Golf ball cores may consist of a single, unitary layer, comprising the entire core from the center of the core to its outer periphery, or they may consist of a center surrounded by at least one outer core layer. The center, innermost portion of the core may be solid, hollow or liquid-, gel-, or gas-filled. The outer core layer may be solid, or it may be a wound layer formed of a tensioned elastomeric material. Golf ball covers may also contain one or more layers, such as a double cover having an inner and outer cover layer. Additional layers may optionally be disposed between the core and cover in the golf balls of the present invention, at least one layer is formed from a composition comprising an elastic protein as described below.

The elastic protein of the present invention may be any naturally occurring or engineered protein, peptide, or polypeptide that has resilience properties suitable for use in golf ball compositions. Such proteins may have particularly suitable resilience properties when crosslinked. In one embodiment, the elastic protein of the present invention is selected from resilin, titin, elastin, fibrillin, gluten, gliadin, abductin, byssus, spectrin, collagen, and spider silks.

In a particular embodiment of the invention, the elastic protein comprises crosslinked recombinant resilin. The following procedure is suitable for preparing crosslinked recombinant resilin. The first exon of the Drosophila melanogaster CG15920 gene, which encodes an amino-terminal domain in the native protein comprising 17 copies of the putative elastic repeat motif, GGRPSDSYGAPGGGN, is cloned and expressed as a soluble protein in Escherichia coli. The resulting soluble resilin protein is then crosslinked by establishing conditions for the formation of dityrosine crosslinks between soluble proteins to produce a solid material. A non-limiting example of such crosslinking method is Ru(II)-mediated photocrosslinking, which provides a rapid, quantitative and controllable conversion of the soluble monomer to a high molecular weight polymeric material. For a more detailed description of the cloning, expression, and crosslinking of recombinant resilin, reference is made to “Synthesis and properties of crosslinked recombinant pro-resilin,” Nature, vol. 437, pages 999-1002 and Supplementary Information pages 1-17 (2005), the entire disclosure of which is hereby incorporated herein by reference.

In a particular embodiment, the elastic protein has a resilience of greater than 80%, or at least 85%, or at least 90%, or at least 92%, or at least 95%. In another particular embodiment, the elastic protein has a modulus at 100% of less than 7 kPa, preferably 6 kPa or less, more preferably 5 kPa or less, more preferably from 1 kPa to 5 kPa, more preferably from 1 kPa to 3 kPa, and even more preferably 2 kPa. Resilience and modulus, as used herein, are measured on samples in buffer on an Instron Tensile Tester (model 4500) at a rate of 5 mm/min at a temperature of 21° C. Swollen strip samples (7 mm×1 mm), having a gauge length of 5 mm, are cycled initially up to a strain of about 200%. The maximum strain is increased successively in steps of 25-50% until failure occurs. Resilience is calculated from the ratio of the area under the retraction curve to the area under the extension curve. The stress at 100% strain on the extension curve is taken as the secant modulus at 100%.

In another particular embodiment, a sphere formed from the elastic protein has a coefficient of restitution (“COR”) of at least 0.810, or at least 0.815, or at least 0.820, or at least 0.850, or at least 0.900, or at least 0.910, or at least 0.920, or at least 0.930, or at least 0.940, or at least 0.950. As used herein, COR is defined as the ratio of the rebound velocity to the inbound velocity when balls are fired into a rigid plate. In determining COR, the inbound velocity is understood to be 125 ft/s.

In another particular embodiment, the elastic protein is a crosslinked material comprising a plasticizer, such as water, in an amount of at least 75 wt %, preferably at least 80 wt %. In yet another particular embodiment, the elastic protein has a density of less than 1.50 g/cm³, preferably less than 1.40 g/cm³, more preferably less than 1.35 g/cm³, and even more preferably 1.33 g/cm³.

Compositions of the present invention comprising an elastic protein may also contain one or more additives in an amount of from 0 wt % to 60 wt %, based on the total weight of the composition. Suitable additives include, but are not limited to, chemical blowing and foaming agents, optical brighteners, coloring agents, fluorescent agents, whitening agents, UV absorbers, light stabilizers, defoaming agents, processing aids, mica, talc, nano-fillers, antioxidants, stabilizers, softening agents, fragrance components, plasticizers, impact modifiers, TiO₂, acid copolymer wax, surfactants, and fillers, such as zinc oxide, tin oxide, barium sulfate, zinc sulfate, calcium oxide, calcium carbonate, zinc carbonate, barium carbonate, clay, tungsten, tungsten carbide, silica, lead silicate, regrind (recycled material), moisture scavengers, moisture barrier materials and layers thereof, and mixtures thereof. Suitable additives are more fully described in, for example, U.S. Patent Application Publication No. 2003/0225197, the entire disclosure of which is hereby incorporated herein by reference.

Elastic protein-containing compositions of the present invention can optionally be blended with thermoplastic and thermoset materials, including, but not limited to, ionomers, acid copolymers, engineering thermoplastics, highly neutralized polymers, polybutadienes, polyurethanes, polyesters, thermoplastic elastomers, and other conventional polymeric materials.

In golf balls of the present invention, at least one layer is formed from a composition comprising an elastic protein. The layer(s) formed from the elastic protein-containing composition may be in the form of a solid or a fluid, such as a liquid or a gel.

Due to the high resilience of elastic proteins, compositions comprising such proteins can be used as the primary source of resilience in golf balls. Thus, in a particular embodiment, the present invention relates to a golf ball having one or more layers, wherein each of the ball's layers is formed from a composition which is substantially free of conventional rubber, or which comprises from 0 wt % to 5 wt %, or from 0 wt % to 3 wt %, or from 0 wt % to 1 wt % of conventional rubber. “Substantially free,” as used herein, means that the composition does not contain conventional rubber, or includes one or more conventional rubbers in an amount of less than 0.5 wt %, based on the total weight of the composition. “Conventional rubber,” as used herein, includes ethylene propylene rubber (“EPR”), ethylene propylene diene rubber (“EPDM”), styrenic block copolymer rubbers (such as SI, SIS, SB, SBS, SIBS, and the like, where “S” is styrene, “I” is isobutylene, and “B” is butadiene), butyl rubber, halobutyl rubber, copolymers of isobutylene and para-alkylstyrene, halogenated copolymers of isobutylene and para-alkylstyrene, natural rubber, polyisoprene, copolymers of butadiene with acrylonitrile, polychloroprene, alkyl acrylate rubber, chlorinated isoprene rubber, acrylonitrile chlorinated isoprene rubber, and polybutadiene rubber.

The high resilience of elastic proteins may also provide for golf ball layers having a higher resilience than in previously known layers. Thus, in a particular embodiment, the present invention relates to a golf ball having a core formed from an elastic protein-containing composition, wherein the core has a COR of at least 0.810, or at least 0.815, or at least 0.820, or at least 0.850, or at least 0.900, or at least 0.910, or at least 0.920, or at least 0.930, or at least 0.940, or at least 0.950.

The elastic protein-containing composition may also provide for golf ball layers that are softer than previously known layers. Thus, in a particular embodiment, the present invention relates to a golf ball having a core formed from an elastic protein-containing composition, wherein the core has a compression of less than 90, or less than 80, or less than 60, or less than 40, or less than 30, or less than 20.

In a preferred embodiment, the present invention relates to golf ball cores having both a COR of at least 0.800, or at least 0.810, or at least 0.815, or at least 0.820, or at least 0.850, or at least 0.900, or at least 0.910, or at least 0.920, or at least 0.930, or at least 0.940, or at least 0.950; and a compression of less than 90, or less than 80, or less than 60, or less than 40, or less than 30, or less than 20.

Golf balls of the present invention can be wound, one-piece, two-piece, or multi-layer balls, so long as at least one layer is formed from an elastic protein-containing composition. In golf balls having two or more layers formed from an elastic protein-containing composition, the elastic protein used for one layer may be the same or a different elastic protein used for another layer. The layer(s) formed from the elastic protein-containing composition can be any one or more of a core layer, an intermediate layer, or a cover layer.

In one embodiment, the golf ball is a one-piece golf ball formed from an elastic protein-containing composition.

In another embodiment, the golf ball is a two-piece or multi-layer ball wherein at least one layer is formed from a composition comprising an elastic protein. The elastic protein-containing composition may be present in a core layer, a cover layer, an intermediate layer (in the case of multi-layer balls), or a combination thereof.

In a particular embodiment, the golf ball is a two-piece ball comprised of a core and a cover, wherein the core is formed from an elastic protein-containing composition. In a particular aspect of this embodiment, the core has an Atti compression of 110 or less. In another particular aspect of this embodiment, the ball has an Atti compression of 110 or less. Preferably, the compression of the ball is from 1 to 1.3 times the compression of the core. In another particular aspect of this embodiment, the cover has an outer surface hardness of 62 Shore D or greater, preferably 65 Shore D or greater.

In another particular embodiment, the golf ball is a two-piece ball comprised of a core and a cover, wherein the core is formed from an elastic protein-containing composition. In a particular aspect of this embodiment, the core has an Atti compression of 70 or less. In another particular aspect of this embodiment, the ball has an Atti compression of 80 or less. Preferably, the compression of the ball is from 1 to 1.3 times the compression of the core. In another particular aspect of this embodiment, the cover has an outer surface hardness of 65 Shore D or less, preferably 62 Shore D or less.

In another particular embodiment, the golf ball is a multi-layer ball comprised of a core, an intermediate layer, and a cover, wherein the core and/or the intermediate layer is formed from an elastic protein-containing composition. In a particular aspect of this embodiment, the core has an Atti compression of 100 or less. In another particular aspect of this embodiment, the ball has an Atti compression of 100 or less. In another particular aspect of this embodiment, the cover has a surface hardness of 65 Shore D or less, preferably 62 Shore D or less, and more preferably 60 Shore D or less. In another particular aspect of this embodiment, the intermediate layer is harder than the cover and the core, wherein hardness is measured on the outer surface of each respective layer. In another particular aspect of this embodiment, the intermediate layer has a hardness of greater than 60 Shore D, the cover has a hardness of less than 60 Shore D, and the core has a hardness of less than 60 Shore D, wherein hardness is measured on the outer surface of each respective layer.

In yet another particular embodiment, the golf ball is a multi-layer ball comprised of a core, an intermediate layer, and a cover, wherein the core has a center and an outer core layer, and wherein the center and/or the outer core layer is formed from an elastic protein-containing composition. In a particular aspect of this embodiment, the overall core has an Atti compression of 100 or less. In another particular aspect of this embodiment, the center has an Atti compression of 20 or less, and the outer core layer has a compression such that the overall core has an Atti compression of 60 or greater. In another particular aspect of this embodiment, the ball has an Atti compression of 100 or less. In another particular aspect of this embodiment, the cover has an outer surface hardness of 65 Shore D or less, preferably 62 Shore D or less. In another particular aspect of this embodiment, the intermediate layer is harder than the cover and the outer core layer, wherein hardness is measured on the outer surface of each respective layer. In another particular aspect of this embodiment, the intermediate layer has a hardness of greater than 60 Shore D, the cover has a hardness of less than 60 Shore D, and the outer core layer has a hardness of less than 60 Shore D, wherein hardness is measured on the outer surface of each respective layer.

Golf balls of the present invention generally have a COR of at least 0.790, or at least 0.805, or at least 0.810, or at least 0.815, or at least 0.820, or at least 0.850, or at least 0.900; and an Atti compression of 100 or less, or 90 or less, or 80 or less.

The present invention is not limited by any particular process for forming the golf ball layer(s). It should be understood that the layer(s) can be formed by any suitable technique, including injection molding, compression molding, casting, and reaction injection molding.

When numerical lower limits and numerical upper limits are set forth herein, it is contemplated that any combination of these values may be used.

All patents, publications, test procedures, and other references cited herein, including priority documents, are fully incorporated by reference to the extent such disclosure is not inconsistent with this invention and for all jurisdictions in which such incorporation is permitted.

While the illustrative embodiments of the invention have been described with particularity, it will be understood that various other modifications will be apparent to and can be readily made by those of ordinary skill in the art without departing from the spirit and scope of the invention. Accordingly, it is not intended that the scope of the claims appended hereto be limited to the examples and descriptions set forth herein, but rather that the claims be construed as encompassing all of the features of patentable novelty which reside in the present invention, including all features which would be treated as equivalents thereof by those of ordinary skill in the art to which the invention pertains. 

1. A golf ball having at least one layer formed from a composition comprising an elastic protein.
 2. The golf ball of claim 1, wherein the elastic protein comprises crosslinked recombinant resilin.
 3. The golf ball of claim 1, wherein the golf ball is a one-piece golf ball having a coefficient of restitution of at least 0.815.
 4. The golf ball of claim 3, wherein the ball has an Atti compression of 90 or less.
 5. The golf ball of claim 1, wherein the golf ball comprises two or more layers, and wherein the innermost layer is formed from the composition comprising the elastic protein.
 6. The golf ball of claim 5, wherein the innermost layer has a coefficient of restitution of at least 0.815.
 7. The golf ball of claim 6, wherein the innermost layer has an Atti compression of 90 or less.
 8. The golf ball of claim 1, wherein the golf ball comprises two or more layers, and wherein the outermost layer is formed from the composition comprising the elastic protein.
 9. The golf ball of claim 1, wherein the golf ball comprises an innermost layer, an outermost layer, and at least one intermediate layer, and wherein an intermediate layer is formed from the composition comprising the elastic protein.
 10. The golf ball of claim 1, wherein the composition comprising the elastic protein additionally comprises at least 75 wt % of a plasticizer, based on the total weight of the composition.
 11. The golf ball of claim 10, wherein the plasticizer is water.
 12. A golf ball having at least one layer formed from a composition comprising an elastic protein, wherein the golf ball has a coefficient of restitution of at least 0.815 and an Atti compression of 90 or less.
 13. The golf ball of claim 12, wherein each of the golf ball layers is substantially free of conventional rubbers. 